Founder of American Century Investments Was a Noted Philanthropist

James E. Stowers Jr., who turned a small six-figure investment into one of the nation's largest mutual-fund companies before turning his focus to philanthropy, died Monday at age 90.

A lifelong resident of Kansas City, Mo., Mr. Stowers was known to mutual-fund associates as "the eternal bull" for his faith in markets. Privately held American Century Investments, the company Mr. Stowers founded in 1958, has grown into a fund...